# SEDA Chain Infrastructure
SEDA is a layer one blockchain purpose-built for oracle infrastructure. The SEDA Core Network architecture consists of three interdependent subsystems:
**SEDA Chain** — the canonical ledger where data request settlement occurs. This ensures that every data request is recorded, validated, and economically finalized under Byzantine fault-tolerant consensus.
**Overlay Network** — a distributed system responsible for HTTP fetches from arbitrary public or private data sources. This enables the ingestion of both permissionless and permissioned information streams into the SEDA ecosystem.
**Solver Network** — a specialized routing layer tasked with forwarding data requests from origin networks → into SEDA → and back to the origin networks. This network ensures trustless bidirectional data flow across blockchain environments and SEDA.
At the application layer, Oracle Programs are deployed as customizable smart contracts. Unlike static price feeds, Oracle Programs allow developers to:
* Define bespoke data aggregation methodologies.
* Incorporate premium or proprietary data sources.
* Apply arbitrary computation (e.g., weighted indexes, smoothing filters, econometric adjustments).
Formally, an Oracle Program can be described as:[](https://x.com/sedaprotocol/article/1958152568682504334/media/1958149902568955904)
where Di are individual data sources, and f is a developer-defined transformation (aggregation, filtering, computation). The output y is an on-chain data feed that protocols can consume.
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